1. Field of the Invention
The present invention relates to a system for protecting a passenger from a side collision of an automotive vehicle.
2. Description of Related Art
A system for protecting a passenger from a side collision (a door of an automobile collides with an obstacle) has been known hitherto. An example of such a system is disclosed in JP-A-2-249740. In this system, a side collision is detected based on pressure changes in an inner space of a door. Namely, it is determined that a side collision occurred when the pressure in the inner space of the door exceeds a predetermined pressure level.
In this system, however, there is a possibility that a side collision is erroneously detected because the pressure in the inner space of the door may become higher than the predetermined level when no side collision occurs. A door of an automobile may be deformed by some other reasons than a side collision because a rigidity of an inner panel of a door is not very high. For example, when an open door is abruptly closed, a pressure in the inner space of the door increases. When a front airbag is inflated, the pressure in the inner space of the door increases. In particular, the pressure increase is predominant when the front airbag is inflated under a condition that all the windows are closed. There is a possibility, in the conventional passenger-protecting system, that a side airbag is unnecessarily inflated based on the pressure increase in the inner space of the door that is caused by reasons other than the side collision.